Vehicle engines employ cooling systems to remove excess heat generated during the combustion process, to increase engine efficiency and prevent engine overheating. Many cooling systems utilize liquid coolant as opposed to air cooling systems to remove greater amounts of heat from the engine due to the significantly higher thermal mass of coolant when compared to air. However, liquid cooling systems may experience leaks that can lead to engine overheating and component degradation.
Cooling system diagnostics have been developed to determine errors and failures in engine cooling systems. U.S. Pat. No. 8,370,052 discloses a cooling system diagnostic algorithm is implemented during start-up to determine if there is a cooling system error. However, leaks in the cooling system disclosed in U.S. Pat. No. 8,370,052 may go undetected for a number of reasons, such external environmental conditions as well as the size, location, and/or type of the coolant leak. For instance, smaller coolant leaks can be more difficult to detect and may be attributed to expected pressure fluctuations in the cooling system. Additionally, implementing the cooling system diagnostic algorithm only during engine start-up limits the timeframe during which cooling system errors can be detected, decreasing the likelihood of error determination.
The Inventors have discovered a novel strategy for implementing cooling systems diagnostics. As such in one approach a method for operating an engine cooling system is provided. The method includes monitoring a coolant temperature profile after engine shut-down and indicating a coolant level based on the coolant temperature profile determined after engine shut-down, for example the method may include indicating a low coolant level to an operator. In this way, coolant leaks can be detected during engine shut-down, expanding the timeframe over which leaks can be detected. As a result, the likelihood of engine overheating is reduced. Furthermore, using the coolant temperature profile after engine shut-down to determine cooling system errors enables smaller coolant leaks to be detected by the diagnostic routine when compared to previous diagnostic routines due to the predictable decay of the coolant temperature profile during shut-down. Consequently, cooling system diagnostics are improved when a coolant temperature decay profile is utilized. Additionally, determining coolant leaks during engine shut-down increases the likelihood of a vehicle operator recognizing the indication of the low coolant level and subsequently servicing the cooling system. In one example, the indication of the low coolant level may also be based on external environmental conditions, to further improve diagnostic accuracy.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. Additionally, the above issues have been recognized by the inventors herein, and are not admitted to be known.